Romans used letters from the alphabet rather
than figures (digits) to write out their numbers. The letters that they
used are listed in the table on the right. So, for example, if a Roman
wanted to write the number 150, he would write CL.

Here are some other examples of numbers
written with Roman numerals. Check through all of them to make sure that
you understand how the system works.

VI = 6, VII =
7, VIII = 8,XV
= 15

XXX = 30,LX = 60, LV = 55

CC = 200, DCC =
700, MMC
= 2100

The examples above are straightforward
and simple. However, there is a slight complication! When a letter that
is worth less is written before a letter
that is worth more, then you need to do a subtraction
to figure out what number is being written.

I

=

1

V

=

5

X

=

10

L

=

50

C

=

100

D

=

500

M

=

1000

Here are some examples of
these.

IV = 4, IX =
9, XL = 40, XC=90, CM=900

With large numbers, it sometimes helps to
underline the pairs of letters where a subtraction is required. For
example, ...

CIX =
109, XCI = 91, MCMII =
1902, MMCMLXIV = 2964

The examples that follow become
increasingly complex but the same principles apply. Make sure that you
understand each of them.

XIV = 14, XX1X =
29, LIV = 54,

LVI = 56, XXIV =
24, XIX = 19

LIX = 59, LXVIII =
68, LXXVII = 77

CIX = 109, MMC =
2100,MCM
= 1900

DCL = 650, MCMVC
= 1995, MCMIC = 1999, MIM = 1999

NOTE: As a general rule,
only one letter that is
worth-less-than-the-one-that-follows is permissible, though this event may
occur more than once in a given number. So, for example ...